4/ The Cal 906.

Apr 08, 2014,03:13 AM
 



The Cal 906 is the last automatic chronometer movement produced by the Manufacture.

In fact, JLC made 7000 Cal 906, since 1973, till 1975.

Some were housed in JLC watches, others were provided to Vacheron Constantin for their Chronometre Royal " automatic ".

According to the Heritage Gallery, 3060 Cal 906 were housed in 3 watch references: 24 000, 24 001 and 24 002, both being Chronometers.

The 24 000 was produced in 520 pieces, and in steel only.









The 24 001 was produced in 105 pieces in yellow gold, and 1050 pieces in steel.





The 24 002 was made in 234 pieces in yellow gold, and 1151 watches in steel.





All the 906 Chronometers have a screw in case back, with the word Chronometer engraved.

With these 24 000 / 24 001 and 24 002 references, the plexy is not used anymore, changed for a sapphire. A small change, announcing the modern times.

As for the movement, the Cal 906 is a 21 jewels automatic " engine ", quite brutal in its look, 28 mm big, 4, 65 mm high, beating at the pace of 28 800 alternances per hour, adjusted to 5 positions and temperatures.

It has a shock protection ( Kif Elastor ), a fine regulation system and a curious stop second, which is this blue plastic lever located close to the balance Wheel.





A last detail on this movement, the quick setting of the date, through pulling, then pushing the crown, which is a quite fragile system.

With the Cal 906 ends the Vintage Jaeger-Lecoultre Chronometer History... An History which will re born with the Master 1 000 Hours Control in 1992... But that is another story, which may soon have some further developments and chapters...

Best,

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An essay on Jaeger, Lecoultre, Jaeger-Lecoultre and Chronometry.

 
 By: amanico : April 8th, 2014-02:58
INTRODUCTION: Let's focus on an interesting and fascinating topic, the Vintage JLC Chronometers. Why Vintage only? Because we can consider almost all the modern production, since 1992, as Chronometers. Here is what I wrote in the article dedicated to prec...  

Part I: The Roots of Chronometry.

 
 By: amanico : April 8th, 2014-02:59
We can already answer to one question: We didn't have to wait for wristwatches to see some Chronometers, at the Grande Maison. Another question receives an answer: The Cal 21 RV is the first Chronometer known from the Grande Maison. Let's see all that in ...  

What an incredible article!

 
 By: 4Js : April 8th, 2014-04:15
I cannot believe the amount of work you had to do here. The pix are fantastic. The depth of information is astounding along with the history. I will have to bookmark this one I knew I would be panting on this. And now I see why you are panting! Your finge... 

Thousand thanks for your kind words. This is something I wanted to write for a long time.

 
 By: amanico : April 8th, 2014-21:29
As Chronometry is a theme dear to my heart. Thank you, once again, Joe. Best, Nicolas

As a token of appreciation, please let me add...

 
 By: blomman Mr Blue : April 8th, 2014-12:45
A document that feels appropriate to add to this post. A 1949 ad - stating the results from the 1948 Chronometre contests... Notice the number in the ad: 464254 and 464260. Then look at the number of the the movements in your post! 464254 - it is the same...  

Now, I am impressed. That is some serious investigation, Blomman.

 
 By: amanico : April 8th, 2014-21:32
Unbelievable. Thank you SO MUCH, my friend. Nicolas

I could not believe my eyes when...

 
 By: blomman Mr Blue : April 8th, 2014-23:08
I compared the number in your photos and the ad! How often do you get to see the exact movement, 66 years later?! :) Best, my friend Blomman

Well, there were a few of these watches which attended the Chronometry contests...

 
 By: amanico : April 9th, 2014-03:18
BUT it is breathtaking to see such a thing! Best, Nicolas

PART II: THE BIRTH OF CHRONOMETRY IN VINTAGE JLC WRISTWATCHES.

 
 By: amanico : April 8th, 2014-03:05
: Here, it is indispensable to spend some time on the definition of a Chronometer. According to Mr L. Defossez, who published an article in the Société Suisse De Chronométrie, there was an evolution in the definition of a Chronometer: - In 1714, the engli...  

Sorry, but I can't resist adding...

 
 By: blomman Mr Blue : April 8th, 2014-12:58
These to this fantastic post! :) Hope you forgive me, my friend... Best Blomman ...  

Aahh.. So I see, also you have the (J)LC Military Trio in your realm.. :))

 
 By: hs111 : April 8th, 2014-13:55
.. the notorious Blomman- special sleeve : long, deep and full of surprises, sometimes.. And yes, the Militaries play a certain role in chronometry reviews . Best, my friend ! hs

You know me, my friend....

 
 By: blomman Mr Blue : April 8th, 2014-14:10
I can't help myself... The MIL's is a MUST for this theme! :) Best Blomman

Just another amazing post by an absolutely amazing...

 
 By: elliot55 : April 9th, 2014-07:44
... Purist. I just received a JLC pocket watch converted to a wristwatch. Will send some photos later! Tout le meilleur mon ami - Scott

PART THREE: THE JLC CIVILIAN CHRONOMETERS.

 
 By: amanico : April 8th, 2014-03:07
Another time, another state of mind... In the Fifties, Humanity saw the most inspiring, crazy and enthusiastic projects and challenges, on Earth as well as in the Space... Science and Adventures. When it comes to Chronometry and Jaeger-Lecoultre, two date...  

1/ The Geophysic.

 
 By: amanico : April 8th, 2014-03:08
Among all the watches from the Jubilé Collection, the most famous is certainly, and by far, the E 168. The strong interest of the Geophysic lies in the fact that it the the addition of History, Horology and aesthetics. Through this reference, Jaeger-Lecou...  

Again, please let me add some additional documents to this post...

 
 By: blomman Mr Blue : April 8th, 2014-13:17
You know my love for the Geophysic and the Jubilé collection... Obsessed by the Geophysic...? Yes, you might say that I am...! :) Best Blomman ...  

My pleasure! :) [nt]

 
 By: blomman Mr Blue : April 10th, 2014-02:11

=) [nt]

 
 By: blomman Mr Blue : April 10th, 2014-02:12

10:09:18

 
 By: AndrewD : April 10th, 2014-19:37
A perfectionist after my own heart. Congratulations on the two Chronometers ... and for displaying them as they were intended. A

Thank you, my friend! :) [nt]

 
 By: blomman Mr Blue : April 11th, 2014-02:28

2/ The Mysterious Master Mariner Chronometer.

 
 By: amanico : April 8th, 2014-03:10
To say that this Chronometer is a mystery, is a sweet euphemism. No hint of its existence in the Lecoultre archives, since they were lost. But it has been mentionned in several documents, such as: The Geophysic Leaflet: A close up of a text, on the left p...  

The case of the Master Mariner is fantastic!

 
 By: blomman Mr Blue : April 8th, 2014-13:23
I still haven't found one... But I do have some documents to share... Best Blomman ...  

Funny thing with the MM is that....

 
 By: blomman Mr Blue : April 10th, 2014-02:13
This is the only watch where it's easier to find documentation that the actual watch! Best Blomman

I own me but...

 
 By: AmericasLawyer : June 24th, 2016-23:36
Mine has the "torpedo" style indices but the hands are just like the Geophysic. Lance

3/ The Geomatics.

 
 By: amanico : April 8th, 2014-03:11
Yes, the plural has to be used, as there were different Geomatics, made since 1962 to 1970 ( round cases ) and from 1970 to 1974 ( tonneau shaped case ) for a total of 4351 round cases produced ( 2000 in stainless steel, 1578 in yellow gold, 773 in rose g...  

E 560... Such a cool watch!

 
 By: blomman Mr Blue : April 8th, 2014-13:35
Now you made me drool....! :) And the chronometre papers of the RG...! :) Best Blomman ...  

OK, now I bite my lip! ;) [nt]

 
 By: blomman Mr Blue : April 10th, 2014-02:14

4/ The Cal 906.

 
 By: amanico : April 8th, 2014-03:13
The Cal 906 is the last automatic chronometer movement produced by the Manufacture. In fact, JLC made 7000 Cal 906, since 1973, till 1975. Some were housed in JLC watches, others were provided to Vacheron Constantin for their Chronometre Royal " automatic...  

Wow my friend!!!

 
 By: Ares501 - Mr Green : April 8th, 2014-04:56
You made an Opus Dei :) That is indeed one big beautiful post about JLC chronometry filled with amazing data and gorgeous pictures Kudos! Time spent in making such epic post is truly amazing surely something to return to on many occasions. Gratefully your... 

It doesn't get any better than this

 
 By: Spellbound : April 8th, 2014-05:03
I am looking forward to your first reference book. With this post, the sharp photos from your new Leica, you certainly have enough material to complete a couple of chapters. Signed copies of the new book for all Purists! You are truly the Master JLC Moder... 

Thanks for the very kind words, Dean. It was an intense pleasure to work on it.

 
 By: amanico : April 8th, 2014-21:54
I should also thank the JLC Heritage Gallery for their help. They provided me some amazing documents and Pocket watches! Best, Nicolas

You know I'm waiting....

 
 By: watchme : April 8th, 2014-08:51
For what this is all leading up to..... ;-) Dean

I know, I know... IT is a matter of time...

 
 By: amanico : April 8th, 2014-21:49
10th of April, 8 PM, Paris Time? ;) Best, Nicolas

Caramba.....what a magnificent post

 
 By: Bobbe : April 8th, 2014-10:56
Nicolas, 'the JLC-professor, my compliments. What an impressive post. I've never seen anything like this before on a watch-forum, and I've got a lot of forums under my favorites. Like we say in Holland, chapeau!! Well done. All the best, Bobbe

Thank you Bobbe.

 
 By: amanico : April 9th, 2014-09:41

Not the prettiest to look at, not the most beautiful decoration on the movement...

 
 By: blomman Mr Blue : April 8th, 2014-13:46
But, for sure the most Super Funky! :) Am I obsessed by JLC Chronometres...? YES, indeed I am! :) Again, Nicloas - thank you for this stunning post about one of my favourite topics! Best, my dear friend Blomman ...  

Wow!! - really like your Duo of Chronometres shown here.. The 24000 must be great in real

 
 By: hs111 : April 9th, 2014-05:18
.. Congratulations, my Nordic friend ; very happy for you! - Both are nice, but I prefer the first, if you allow .. Best, hs

Thank you, HS! :)

 
 By: blomman Mr Blue : April 10th, 2014-02:15
Yes, the 24000 is Super Funky! :) Thank you, my friend! Best Blomman

What to say!!????...............

 
 By: Sandgroper : April 12th, 2014-07:48
Fantastic Review, what an effort, BRAVO and thank you Nicolas:) Cheers Francois from Down Under

Yes, the IGY logo...

 
 By: blomman Mr Blue : April 8th, 2014-13:04
JLC was actually using the planets and solar system already in 1947... :) Best Blomman ...  

Our host creates JLC's own "Opus" series...

 
 By: Tim_M : April 8th, 2014-04:57
Nicolas, This post is magnificent. The scope and rigor of the research and writing surpasses many of the dedicated commercial watch blogs. Entries like your JLC Chronology epic are what makes 'prosite/PuristS great. Thank you; like 4J, I'm bookmarking thi... 

Thank you so much for these kind words, Tim.

 
 By: amanico : April 9th, 2014-08:56
The funny thing is that that review will also help me on my articles to come. As for the Master Tourbillon, yes, it is in the - 1 / +6 sec per day range. Which are prudent specs. All the best, Nicolas.

WaBooom!.. What a splendid and so enjoyable post & essay !.. Thank you so much !

 
 By: hs111 : April 8th, 2014-05:24
.. actually have been devouring this well composed write-up, with so much of data, so many details and other valuable informations.. In reality, you kind of outdid yourself, unbelievingly so - also each "module" & part is something to read, re-read again ... 

Nicolas, first of all I would like...

 
 By: blomman Mr Blue : April 8th, 2014-12:26
To thank you for an fantastic post! This time you have really outdone your self! :) To me Chronometry is the essence of watchmaking. Yes, I know we are talking about Tourbillons, MR's and all of these high end complications... BUT, if the accuracy is not ...  

Accuracy is vital for me as well.

 
 By: amanico : April 9th, 2014-09:12
Without accuracy, we would systematically be too late to bid on these Watch auctions. ;) More seriously, what you are saying is Antoine Lecoultre's philosophy... First, work on accuracy, then on some sophistications / complications. Best, and thanks for t... 

Wow, that is good stuff!

 
 By: stromer : April 8th, 2014-14:08
My god, what did you say? Two years to prepare this post? Now I fully understand why. What a lot of data to find, to collect, to check and to cross check. Let alone the great quality pictures. Chronometry is one of the things I like most about watches and... 

Gracias, Juan! [nt]

 
 By: amanico : April 9th, 2014-10:17

Nicolas.....

 
 By: shipkeeper : April 9th, 2014-14:03
.......Ud se lo merece caballero, impresionante su estudio!! In my days when sailing the Chronometer are essential and without their accuracy could be here or there and sometimes beyond of track was very very ...bad! All the best My friend! Juan

Accuracy is everything, I totally agree with that, Martin.

 
 By: amanico : April 9th, 2014-09:46
Aaah, if you want to see a Geophysic in the real, I think it will soon be possible... ;) Thanks for your words of encouragement, my friend. Nicolas

This essay will serve as a reference post for many years to come!

 
 By: HerrK : April 9th, 2014-08:22
Concise and exhaustive – very impressive, Nicolas! The only question that lingers: why did JLC mark only some of the 24000-42s as “CHRONOMETRE” on their dials but not all of them – extrapolating from the pictures that can be accessed on the web it might e... 

I see what you mean...

 
 By: amanico : April 9th, 2014-08:52
You saw the mention Chronometer on the 24 000 only on the Master Mariner dial configuration, maybe? This is the only configuration I saw with this mention on the dial. Not on the earlier 24 000, the one I posted. The MM 24 000 came in 1974, this is what I... 

Well, my 24000-42-165 is just ...

 
 By: HerrK : April 9th, 2014-09:17
... a handfull of digits from Ilja's (pictured in Zaf's book) with respect to case numbers making the case about 300 digits younger than the one you show in your post. Further the movement is about 250 Digits older than the one you show in your post. Stil... 

Do you have doubts about what I said?

 
 By: HerrK : April 9th, 2014-14:11
Trust me Nicolas! ;-) It is a pretty ordinary 24000-42 with blue dial (165). Here you go: JLC 24000-42-165 CHRONOMETRE Cheers, Christian ...  

Naaah! The only 24000 I saw with the mention Chronometer on the dial was

 
 By: amanico : April 9th, 2014-14:16
The Master Mariner version. The same than mine with this mention, I never saw! Wow! Best, and thanks, Christian! Nicolas

There may be a misunderstanding ...

 
 By: HerrK : April 9th, 2014-14:39
... or I may be just ignorant: could you tell me the difference between a 24000-42 Master Mariner and an ordinary 24000-42 please. I thought that Master Mariner was nothing but a name for the very 24000-42 (and others). Christian

Different? In which way? Now don't tell me that ...

 
 By: HerrK : April 10th, 2014-00:05
... the Master Mariner has the CHRONOMETRE imprint! ;-) Btw.: the Master Mariner 24000 in the 1975 blue/white catalog does not have the imprint. Christian

What a mess! :) [nt]

 
 By: amanico : April 10th, 2014-00:09

a guess (updated)

 
 By: Ilja : April 9th, 2014-14:12
I got my watch from the original owner, located in the US. So maybe the lack of Chronometre imprint on dial is a sign of region the watch was originally sold. But I doubt to find enough origin details since watches tend to go trough several hands before e... 

Could be an explanation, but ...

 
 By: HerrK : April 9th, 2014-14:53
... why wouldn't be US market watches signed CHRONOMETRE? Other JLC models were. The coloured 1975 catalog in the post shows a 24000-42-165 with the imprint CHRONOMETRE. With the case number of mine just a handful of digits from yours one could be led to ... 

statistics...

 
 By: Ilja : April 9th, 2014-15:18
are often a useful instrument to figure out, but in this case is to less material available. I made some amazing discoveries regarding the (J)LC Weems using statistics, but will -if ever- publish them with British Horological Journal. From the given produ... 

Please explain.

 
 By: Ilja : April 10th, 2014-00:47
What makes a cal. 906 Chronometer on one hand a 'Master Mariner' while other with indeed same reference from the same line, as you state are non Master Mariner?! JLC had several lines of watches in the 70's. ie De Luxe, Vogue, Memovox, Master Mariner, Clu... 

To my eye that difference just seems to be ...

 
 By: HerrK : April 10th, 2014-02:24
... a Saudi Arabian emblem by the 9 (crossed swords and a Palm tree). Looks like Mehltretter's 24000-42 has been especially issued for some Saudi Arabian authority. Christian

I can't see very well, indeed, since the photo has a low resolution.

 
 By: amanico : April 10th, 2014-02:40
But it is true that, as Master Mariner is not always written on the dial as it is a family name, it is hard to see the différences. I will post somethingon the MM family, one day. Best, Nicolas

Well...

 
 By: Ilja : April 10th, 2014-06:36
This does not add any credibility as you play a simple lawyer's game by pushing a disclosure into unspecified future. Of course with intentional smoke-screen, pointing away from the question/topic by generalizing it into a wide theme. Bravo, but busted. M... 

I dare not call, Ilja. I always considered 24 000 like mine as a non MM watch.

 
 By: amanico : April 10th, 2014-06:50
Now, it has been said and written that some were MM. Is this due to the fact that some other watches were not mentionning MM on their dial and still are, I don't know. I never saw a MM 24000 which doesn't mean that I saw all and that I can deny the fact t... 

and again...

 
 By: Ilja : April 10th, 2014-08:09
...lawyer's rhetorics, unspecified hear saying, no sources whatsoever. No mate, you are on the hook. Yet you consider, while before it was like a fact. Thats how false legends are born. You give no proof or even a hint since you can't, is this the way ser...  

08.07.2014

 
 By: HerrK : April 10th, 2014-09:27
That date will mark the tercentenary of the Longitude Act! I doubt that JLC will go for a COSC-rated watch for the tercentenary. But the rumours about an all new evaluation and certification of chronometric accuracy could make sense with respect to that d... 

Hi IIja. Is everything all right?

 
 By: Sandgroper : April 12th, 2014-08:47
...perhaps, global warming? Cheers Francois from Down Under

Thanks for asking...

 
 By: Ilja : April 12th, 2014-09:22
guess latest sun's outburst resulted some effects. Cheers. I.

I think I responded to the wrong person........

 
 By: Sandgroper : April 12th, 2014-08:39
To my eyes, it seems that there is an error on page 91, when describing the picture of the caliber P 478/BWSbr.....the caption says Caliber P 78/BWSbr.... so, the P 478 becomes the P 78??!!!! A discrepancy of 400!!!!LOL!!! Sincerely, does it matter?? Perh... 

Never mind! But pardon me to …

 
 By: HerrK : April 13th, 2014-07:25
… mark a mistake of yours: you obviously confused the number of a caliber with the movement number! The number of a caliber is nothing but the name of a caliber, used to distinguish different calibers - whereas the movement number is the production number... 

To my eyes it seems that there is.......

 
 By: Sandgroper : April 12th, 2014-08:22
an error on page 91, when describing the picture of the caliber P 478/BWSbr...............the caption says Caliber P 78/BWSbr;)....the P 478 becomes P 78???!!!! A discrepency of 400..LOL!!!!!....Sincerely, does it matter;) Cheers Francois from Down Under

A typo, for sure. [nt]

 
 By: amanico : April 28th, 2016-08:05

Here we are

 
 By: Dje : April 9th, 2014-09:38
Congratulations Nicolas, Your essay is terrific and will catch and enthusiast all JLC chronometry watches fans for Long. You know that it is also my favourite subject, although I'm far from your knowledge and experience. I'm just glad (and thankful) to al... 

Yes, a Mark 11 would be a superb addition in your collection, my friend.

 
 By: amanico : April 10th, 2014-02:37
Chronometry and accuracy are all for a Watch, I agree with that. It is so fascinating to see watchmakers trying to win the accuracy battle! Thanks for your feedback, my friend. Nicolas

Incredible article

 
 By: vitalsigns : April 9th, 2014-12:32
Incredile article--a monument to part of JLC's rich history. Thank you for putting this together, a tribute to one of the best maisons in the history of horology. Cheers, John

Great article!

 
 By: RDL : April 11th, 2014-02:38
Huge thanks! Well researched and structured. Super helpful! A real seminal piece for all collectors Best my friend, with a lot of appreciation RDL

Wow! What an article my dear friend!! Congratulations!...

 
 By: Subexplorer : May 13th, 2014-11:15
... just read along all that mine of information and veiwed your always awesome pictures! This surely is a large important post which has demanded you a lot of work and research! I will be reading it again next week end. More slowly and enjoying it fully!...